Chapter 10, Problem 13A

Summary Introduction

To explain:

The differences between the given vocabulary terms.

Introduction:

The study of heredity is called genetics. Gregor Mendel was a mathematician who studied how some characteristics are passed from parent to offspring while others do not. Heredity is passing on of characteristics from parent to offspring. These characteristics are known as traits.

Answer to Problem 13A

Genotype	Phenotype
It refers to the genetic composition of a trait.	It refers to the physical expression of a trait.
This is not visible.	This is clearly visible.
It remains same throughout the lifetime.	It may change with time due to influence of environmental factors.
It is expressed as TT, tt, Tt etc.	It is expressed as tall, short, etc.
It cannot be determined even if the phenotype is known.	It can be determined if genotype is known.

Explanation of Solution

The outward appearance of an organism does not always indicate which pair of alleles are present. The allele pairs in the organism are called genotype. By looking at the organism we cannot tell which genes will pass on to the next generation. Sometimes tall plants when self- pollinated, may produce both tall and short plants. A short and a tall plant on cross pollination may produce all tall plants. Two tall plants may look alike but may have different allele combinations. The way an organism looks or behaves is called phenotype.

A dominant allele is denoted by a capital letter while a recessive allele is denoted by a lowercase letter. T is used to denote allele for tallness and t is used to denote allele for shortness.

Phenotype of a tall plant is tall. Genotype of a tall plant can be TT or Tt . If we know the genotype, we can predict the phenotype. For example, if the genotype of a plant is tt , we can say that the plant will be dwarf.